Lecithin may become contaminated with e.g. poly-aromatic hydrocarbons (PAHs), pesticides and other contaminants during its extraction process from oil seeds. Some of these contaminants, and especially PAHs, can be carcinogenic and pose a problem when the lecithin is to be used in food and animal feed, and especially in infant food products.
Methods for removing contaminants from lecithin are well known in the art. For example, CN 2007/1010356 discloses a method for preparing a powdered lecithin intended for medical use, containing only traces of solvent or coal. The method thereof makes use of supercritical CO2 to extract contaminants from a raw lecithin sample followed by bleaching with active carbon to remove unwanted pigments.
Methods for removing PAHs from liquids have been described in the art. For example, U.S. Pat. No. 6,270,676 describes a process for removing ethers and/or polycyclic aromatic hydrocarbons from water. The process requires adsorbing the contaminants on an adsorber resin of divinyl benzene/styrene copolymer, then desorbing the adsorbed contaminants with steam and finally regenerating the adsorber resin. The methods of the prior art are however not directly applicable to lecithin. This is because lecithin is too viscous. As such, putting the lecithin through a packed column or a filter is very difficult.
A lecithin suitable for use in infant food formulas and having an increased degree of purity together with a method for manufacturing thereof are also known from WO 2009/095435. However, according to this publication the term “purified lecithin” means a lecithin having reduced amounts of triglyceride fractions, e.g. ω6 long chain polyunsaturated fatty acids (LCPUFA). WO 2009/095435 is not concerned with PAH that may be present in the lecithin, nor does it disclose any method that could remove or at least decrease the amount of the PAH.
It is thus an object of the present invention to provide a method for the purification of lecithin that may be capable of effectively and economically removing contaminants such as e.g. PAHs, pesticides, particulates, and the like. A further object of the invention may be to provide a lecithin having reduced amounts of contaminants, e.g. PAH.